Consider    import fileinput    import pathlib    with fileinput.input(files=(pathlib.Path('in.txt'),), inplace=True) as fp:        for line in fp:            print(line, end='')which results in    Traceback (most recent call last):      File "./pathlib-fileinput.py", line 6, in <module>        for line in fp:      File "/Users/zmwang/.pyenv/versions/3.6.1/lib/python3.6/fileinput.py", line 250, in __next__        line = self._readline()      File "/Users/zmwang/.pyenv/versions/3.6.1/lib/python3.6/fileinput.py", line 331, in _readline        self._filename + (self._backup or ".bak"))    TypeError: unsupported operand type(s) for +: 'PosixPath' and 'str'A trivial fix is converting the specified filename to str when assigning to self._filename:    -        self._filename = self._files[0]    +        self._filename = str(self._files[0])